[erlang-questions] [proposal] Declarative syntax for metadata (long!)

Dominic Williams <>
Fri Mar 19 13:44:10 CET 2010

Le 18 mars 2010 à 14:06, Joe Armstrong a écrit :

> I agree, this is one of the things that is missing from Erlang
> I think the problem is one of introspection.
> Basically every "thing" has three representations
>    (1) The external print representation of the thing
>        (ie the thing you type into a module, or in the shell)
>    (2) The parse tree representing (1)
>    (3) The internal compiled form of the thing
> It should be possible to convert at run-time between any of these
> three representations.
> [...]

Joe, and Vlad, what kind of programming problems could be solved more easily thanks to such a feature (which I believe is actually reification, introspection being just the possibility to see - ask questions about - but not manipulate)?

I can see one area which would become much easier to work on: development tools.

But for everyday programming, I'm afraid introducing reification would actually make Erlang less simple, less easy to reason about, less reliable... and these properties of Erlang are more important to me, given that I want to ship working software quickly, than being able to do cool things with reification.

I've always been a fan of Joe's principle that for every thing one adds to Erlang, one should remove something else - so since Joe is supporting adding introspection, I'm interested to hear what he would be prepared to remove in exchange?

Best regards,

Dominic Williams


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